Resources For You

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  4. 5 Unique Types of VoIP Gateways Explained!

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  10. 7 New Capabilities an AI Calling System Offers

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  11. 7 Ways to Optimize AHT

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  12. 9 Key Functions of an SBC Explained

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  13. 10 Benefits of an AI Calling System

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  14. 10 Factors to Consider While Choosing a Webphone

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  15. 10 Important Components of a VoIP Carrier Network Explained

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  16. 10-Point Security Checklist for VoIP Carriers

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  17. 10 Tips For Effective Implementation of LCR

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  18. 10 Webphone Features that Benefit Your Business

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  19. AI Guardrails 101 - Introduction to AI Safety Nets

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  20. AI Guardrails - Types and the Legal Risks They Mitigate

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  21. An Out of the Box Telecoms Network

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  22. Are Call Centers Still Relevant in 2023?

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  23. Automated Dialler vs Manual Dialler - Knowing the 7 Key Differences

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  24. Best Open Source LLMs for Voice AI - A Practical 2025 Selection Guide

    Best Open Source LLMs for Voice AI - A Practical 2025 Selection Guide

  25. Call Center vs Contact Center - Understanding the Differences

    Call Center vs Contact Center - Understanding the Differences

  26. Choosing SIP over TCP,TLS and UDP in 2022

    Choosing SIP over TCP,TLS and UDP in 2022

  27. Class 4 Softswitch vs Class 5 Softswitch - Understanding the Difference

    Class 4 Softswitch vs Class 5 Softswitch - Understanding the Difference

  28. Combatting Covid-19 with Carrier-Grade Communications Solutions to Help Users Work Remotely

    Combatting Covid-19 with Carrier-Grade Communications Solutions to Help Users Work Remotely

  29. Comprehensive Cloud Softswitch Documentation

    Comprehensive Cloud Softswitch Documentation

  30. ConnexCS expands AnyEdge SIP Load Balancer to India

    ConnexCS expands AnyEdge SIP Load Balancer to India

  31. ConnexCS for Africa

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  32. ConnexCS WebPhone SDK Connector

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  33. Conquer Call Issues: A Beginner's Guide to Reading SIP Traces

    Conquer Call Issues: A Beginner's Guide to Reading SIP Traces

  34. Discover the Different Types of NAT: An Essential Guide for Network Administrators

    Discover the Different Types of NAT: An Essential Guide for Network Administrators

  35. Discussing the Future and Top 9 Benefits of WebRTC

    Discussing the Future and Top 9 Benefits of WebRTC

  36. DNO And DNC Lists - Everything Carriers Should Know

    DNO And DNC Lists - Everything Carriers Should Know

  37. Email and SMS Alerts

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  38. Employers' Guide to Winning at Remote Work

    Employers' Guide to Winning at Remote Work

  39. Exploring the Top 10 Types of Web Phones in 2023!

    Exploring the Top 10 Types of Web Phones in 2023!

  40. False Answer Supervision Detection - The Ultimate Tool for Preventing VoIP Fraud

    False Answer Supervision Detection - The Ultimate Tool for Preventing VoIP Fraud

  41. Far-End NAT Traversal - An In-Depth Guide

    Far-End NAT Traversal - An In-Depth Guide

  42. Feature Releases for June 2024

    Feature Releases for June 2024

  43. Feature Releases for July 2024

    Feature Releases for July 2024

  44. From Cost Savings to Mobility - 15 Benefits of Web Phones for Businesses

    From Cost Savings to Mobility - 15 Benefits of Web Phones for Businesses

  45. Get Your FCC Registration Number in 5 Easy Steps!

    Get Your FCC Registration Number in 5 Easy Steps!

  46. How to Build Your API on ConnexCS

    How to Build Your API on ConnexCS

  47. How to Build Your Own Dialer (BYOD) – Part 1

    How to Build Your Own Dialer (BYOD) – Part 1

  48. How to Establish a VoIP Interconnect in 10 Easy Steps

    How to Establish a VoIP Interconnect in 10 Easy Steps

  49. How to Get Operating Company Number (OCN) in 4 Easy Steps

    How to Get Operating Company Number (OCN) in 4 Easy Steps

  50. How to Identify Robocall Scam Traffic - A Comprehensive Guide for Telecom and VoIP Operators

    How to Identify Robocall Scam Traffic - A Comprehensive Guide for Telecom and VoIP Operators

  51. How to Improve CX? Ensure your Call Center Agents are Happy!

    How to Improve CX? Ensure your Call Center Agents are Happy!

  52. How to Prepare for a VoIP Network Security Audit

    How to Prepare for a VoIP Network Security Audit

  53. How to Properly Prepare for Setting up a VoIP Interconnect

    How to Properly Prepare for Setting up a VoIP Interconnect

  54. How to Register for the Robocall Mitigation Database: A step-by-step guide!

    How to Register for the Robocall Mitigation Database: A step-by-step guide!

  55. How to Successfully Implement LCR is 5 Easy Steps

    How to Successfully Implement LCR is 5 Easy Steps

  56. How Using Web Phones Can Benefit These 10 Industries?

    How Using Web Phones Can Benefit These 10 Industries?

  57. How Will AI Voice Agents Impact the Call Center Industry?

    How Will AI Voice Agents Impact the Call Center Industry?

  58. Importance of Balancing Cost Minimization and Reliable Call Quality when implementing LCR

    Importance of Balancing Cost Minimization and Reliable Call Quality when implementing LCR

  59. Introducing ConnexCS WebPhone

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  60. Introducing ConneXML - The Best TwiML Alternative

    Introducing ConneXML - The Best TwiML Alternative

  61. Introducing Smart CLI Select - An Effective Way to Improve your ASR

    Introducing Smart CLI Select - An Effective Way to Improve your ASR

  62. Introduction to AI Voice Agent Guardrails - What They Are and Why Your Business Needs Them

    Introduction to AI Voice Agent Guardrails - What They Are and Why Your Business Needs Them

  63. Is Your Call Center Ready for AI? The 2025 Cost Advantage You Can’t Ignore in India

    Is Your Call Center Ready for AI? The 2025 Cost Advantage You Can’t Ignore in India

  64. LLM Selection Made Simple - Building High-Performance AI Voice Systems

    LLM Selection Made Simple - Building High-Performance AI Voice Systems

  65. LTE vs VoLTE: Diving Into The Differences

    LTE vs VoLTE: Diving Into The Differences

  66. Navigating Cold Calling - UK Compliance for Call Centers

    Navigating Cold Calling - UK Compliance for Call Centers

  67. Operating Company Numbers (OCN) - Understanding Function, Importance and Relevance

    Operating Company Numbers (OCN) - Understanding Function, Importance and Relevance

  68. Populating Our Support Area With Cloud Softswitch Video Guides

    Populating Our Support Area With Cloud Softswitch Video Guides

  69. Predictive Dialler vs Progressive Dialler - Understanding the Differences

    Predictive Dialler vs Progressive Dialler - Understanding the Differences

  70. Preview Dialler vs Power Dialler - Understanding Top 5 Differences

    Preview Dialler vs Power Dialler - Understanding Top 5 Differences

  71. Real-Time Alerting Made Easy with ConnexCS and Pushover

    Real-Time Alerting Made Easy with ConnexCS and Pushover

  72. Rate Card Profit Assurance

    Rate Card Profit Assurance

  73. Redundant Redundancies (Backups of backups)

    Redundant Redundancies (Backups of backups)

  74. Rethink Your Call Center - The 10x Cost Benefit of AI Voice Agents

    Rethink Your Call Center - The 10x Cost Benefit of AI Voice Agents

  75. Revolutionise Your Outbound Calls - 8 Types of VoIP Diallers Explained

    Revolutionise Your Outbound Calls - 8 Types of VoIP Diallers Explained

  76. The Complete Guide to Effective Root Cause Analysis

    The Complete Guide to Effective Root Cause Analysis

  77. Scalability – Grow at Speeds That Suit You

    Scalability – Grow at Speeds That Suit You

  78. ScriptForge – Javascript Routing

    ScriptForge – Javascript Routing

  79. Simplifiying our Softswitch Pricing

    Simplifiying our Softswitch Pricing

  80. SIP 101 - The Best Guide of 2022

    SIP 101 - The Best Guide of 2022

  81. The 3CX Supply Chain Attack - Understanding Everything That Happened

    The 3CX Supply Chain Attack - Understanding Everything That Happened

  82. The 5 Best Strategies for Mitigating Robocall Scams

    The 5 Best Strategies for Mitigating Robocall Scams

  83. The Anatomy of Robocall Scams

    The Anatomy of Robocall Scams

  84. The Art of Cost Optimization - Least Cost Routing and Its 7 Benefits

    The Art of Cost Optimization - Least Cost Routing and Its 7 Benefits

  85. The Best Multi-POP Cloudswitch

    The Best Multi-POP Cloudswitch

  86. The Essential Guide to Business Continuity Plans for VoIP Carriers

    The Essential Guide to Business Continuity Plans for VoIP Carriers

  87. The Essential Guide to Implementing STIR/SHAKEN

    The Essential Guide to Implementing STIR/SHAKEN

  88. The Ultimate Guide to STIR/SHAKEN

    The Ultimate Guide to STIR/SHAKEN

  89. Timeout Protections (SIP Ping, SST)

    Timeout Protections (SIP Ping, SST)

  90. TLS and 2FA Security on the ConnexCS Platform

    TLS and 2FA Security on the ConnexCS Platform

  91. Top 5 Alternative Marketing Strategies for VoIP Businesses

    Top 5 Alternative Marketing Strategies for VoIP Businesses

  92. Top 5 Call Center Challenges and How To Overcome Them

    Top 5 Call Center Challenges and How To Overcome Them

  93. Top 5 Important Types of VoIP Gateways Explained

    Top 5 Important Types of VoIP Gateways Explained

  94. Top 7 Strategies For Ensuring Call Quality While Minimizing Costs with LCR

    Top 7 Strategies For Ensuring Call Quality While Minimizing Costs with LCR

  95. Top 9 Indicators that Help You Identify a Bad Carrier

    Top 9 Indicators that Help You Identify a Bad Carrier

  96. Top 10 AI Voice Agent Platforms in 2025

    Top 10 AI Voice Agent Platforms in 2025

  97. Top 10 Points of Differences Between a Traditional and VoIP Carrier

    Top 10 Points of Differences Between a Traditional and VoIP Carrier

  98. Top 10 Types of Robocall Scams Explained!

    Top 10 Types of Robocall Scams Explained!

  99. Top 10 VoIP Vulnerabilities You Must Know About

    Top 10 VoIP Vulnerabilities You Must Know About

  100. Top Challenges for Carriers in Identifying and Curbing Illegal Robocall Traffic from Upstream Carriers

    Top Challenges for Carriers in Identifying and Curbing Illegal Robocall Traffic from Upstream Carriers

  101. Troubleshooting 4XX Series SIP Call Failures using SIP Traces

    Troubleshooting 4XX Series SIP Call Failures using SIP Traces

  102. Troubleshooting 5XX Series SIP Call Failures using SIP Traces

    Troubleshooting 5XX Series SIP Call Failures using SIP Traces

  103. Understanding Global RTP Servers (Lowest Latency Possible, High Availability)

    Understanding Global RTP Servers (Lowest Latency Possible, High Availability)

  104. Understanding Network Address Translation (NAT) - A Beginner's Guide

    Understanding Network Address Translation (NAT) - A Beginner's Guide

  105. Understanding the 9 Key Objectives of a VoIP Network Security Audit

    Understanding the 9 Key Objectives of a VoIP Network Security Audit

  106. Understanding the Complete Scope of a VoIP Network Security Audit

    Understanding the Complete Scope of a VoIP Network Security Audit

  107. Understanding the Crucial Role of Session Border Controllers in Carrier-Grade VoIP Networks

    Understanding the Crucial Role of Session Border Controllers in Carrier-Grade VoIP Networks

  108. Understanding VoIP Anycast Load Balancing

    Understanding VoIP Anycast Load Balancing

  109. Understanding What a PBX System is and How it Benefits Your Business

    Understanding What a PBX System is and How it Benefits Your Business

  110. Unlocking the Power of Voice - AI Voice Agent Explained

    Unlocking the Power of Voice - AI Voice Agent Explained

  111. VoIP Carrier Network Components - Understanding Session Border Controllers

    VoIP Carrier Network Components - Understanding Session Border Controllers

  112. VoIP Carrier Network Security - How to Conduct Security Audit?

    VoIP Carrier Network Security - How to Conduct Security Audit?

  113. VoIP Carrier's Ultimate Guide to Cleaning Up Their Traffic

    VoIP Carrier's Ultimate Guide to Cleaning Up Their Traffic

  114. VoIP Interconnects - Learning How VoIP Carrier Connect and Exchange Traffic

    VoIP Interconnects - Learning How VoIP Carrier Connect and Exchange Traffic

  115. VoLTE - An Evolution in Voice Communication

    VoLTE - An Evolution in Voice Communication

  116. WebPones Explained: Understanding Web-Based Telephonic Communication

    WebPones Explained: Understanding Web-Based Telephonic Communication

  117. WebRTC 101 - The Best Guide for Beginners

    WebRTC 101 - The Best Guide for Beginners

  118. What Are SIP Traces - A Beginners Guide

    What Are SIP Traces - A Beginners Guide

  119. What Are The Top 10 Essential Call Center KPIs?

    What Are The Top 10 Essential Call Center KPIs?

  120. What Are VoIP Gateways and How Do They Work? A Comprehensive Guide

    What Are VoIP Gateways and How Do They Work? A Comprehensive Guide

  121. What is a Contact Center and Why Does Your Business Need One?

    What is a Contact Center and Why Does Your Business Need One?

  122. What is an AI Calling System?

    What is an AI Calling System?

  123. What is Robocall Mitigation Database? A Guide for Carriers and VoIP Operators

    What is Robocall Mitigation Database? A Guide for Carriers and VoIP Operators

Best Open Source LLMs for Voice AI - A Practical 2025 Selection Guide

Picture a call center transformed into a symphony of seamless conversation powered by AI Voice Agents. Voices that once carried frustration now glide effortlessly through intelligent exchanges.

Imagine your own creation orchestrating these interactions. An AI Voice agent that knows when to pause, when to answer, and when to surprise with a human-like touch.

The thrill of building it yourself is irresistible. The chance to craft every nuance, to shape responses that feel alive rather than scripted. Yet behind this dream lurks a maze: models to tune, latency to trim, context windows to manage, and guardrails to enforce.

This guide is your map! We’ll explore the best open-source LLMs for voice AI.

Together we will break down what truly matters for performance and reliability. All to find out ways to achieve brilliance without being consumed by infrastructure battles.

Why do open source LLMs matter for voice agents?

Why do open source LLMs matter for voice agents?

Open-source LLMs have become the backbone for anyone hunting the best open source LLMs for voice AI. They keep costs predictable, no surprise usage bills, and give businesses the freedom to host on private servers or the cloud of their choice.

Technical teams love them because they allow deep customisation. Need a multilingual, domain-specific voice bot? Open-source models let you fine-tune for accuracy while balancing the unavoidable trade-off: faster responses often mean lighter models, while heavyweight models deliver nuance at the cost of speed.

Why do open source LLMs matter for voice agents?

Yet most existing guides list models without digging into voice-specific headaches like latency ceilings or streaming requirements. Voice agents can’t pause awkwardly mid-sentence like a teenager texting back; they need sub-second response times.

That’s why decision-makers must weigh both performance and real-time conversational flow when choosing an LLM.

The Advantages of Open Source LLMs

The Advantages of Open Source LLMs

Open-source LLMs deliver three decisive advantages for voice AI builders: transparency, control, and cost efficiency.

Transparency ensures visibility into training data, model architecture, and performance benchmarks. These are essentials for compliance-heavy sectors such as finance.

Control allows teams to fine-tune models for latency, accuracy, and domain specificity without waiting on vendor roadmaps. Cost efficiency emerges from avoiding per-request pricing and enabling on-device deployments that reduce inference expenses over time.

Combined, these factors give businesses freedom from vendor lock-in while accelerating experimentation cycles.

Teams can deploy pilots quickly, validate real-world performance, and adapt models as requirements evolve. All of it at a fraction of closed-source development costs.

Selection criteria that matter for voice agents

Selection criteria that matter for voice agents

When choosing the best open source LLMs for voice AI, the details matter as much as the big picture. Engineers and product leads must weigh both performance metrics and operational trade-offs.

Each selection criterion shapes how natural, reliable, and scalable a voice agent will be. Missing one nuance can turn a smooth conversation into an awkward robot monologue.

Real-Time Streaming and Partial Response Support

Voice agents can’t pause for dramatic effect like a Netflix cliffhanger. They need partial responses to start speaking while processing continues.

Test whether the model supports streaming outputs. Measure how quickly the first word emerges and if partial segments update smoothly. Real-time streaming transforms a choppy bot into a conversational companion.

Latency Budget and Round-Trip Targets

Latency Budget and Round-Trip Targets

Sub-second interactions aren’t optional, they’re essential. Every component, from ASR to TTS, contributes to round-trip latency. Map each stage and measure percentiles, not averages.

A 500 ms target feels natural, while anything beyond 800 ms risks user frustration. Fast response is as much about perception as technical speed.

Interruptibility and Turn-Taking Behaviour

Humans interrupt. Your agent must handle it without stuttering. Evaluate how accurately it detects overlaps, cancels partial outputs, and switches context mid-turn.

Poor turn-taking feels robotic and unnatural. Interruptibility ensures conversations flow like a witty banter, not a scripted podcast.

Context Window and Memory Strategy

Context Window and Memory Strategy

Multi-turn dialogues demand memory. Track how accuracy degrades over turns and how retrieval strategies affect context.

Effective context windows prevent repeated questions and maintain coherent conversations. Without it, even the smartest model forgets the user’s last sentence, like someone checking their phone mid-chat.

Model Size, Quantisation, and Hardware Constraints

Bigger isn’t always better. Larger models bring nuance but demand GPU horsepower. Quantisation can shrink models with minimal accuracy loss. Balance size against deployment goals; on-premise for privacy or cloud for heavy reasoning. A lightweight model may respond faster than a heavyweight, even if it sounds less Shakespearean.

Safety, Hallucination Controls, and Guardrails

Safety, Hallucination Controls, and Guardrails

Spoken outputs must be factual and safe. Red-team scenarios, content filters, and guardrails prevent embarrassing or risky hallucinations.

Even the most charming model needs boundaries, or your voice agent might unintentionally quote a Marvel villain mid-demo.

License and Commercial Use Restrictions

Open-source freedom comes with strings attached. Permissive or copyleft licenses affect redistribution and SaaS deployment.

Always verify terms to avoid legal headaches. Knowing the rules upfront keeps your product launch on schedule, without surprise plot twists.

Selection CriterionKey MetricsPractical Thresholds
Real-Time Streaming & Partial ResponsesFirst word latency, partial update frequency≤ 300 ms for first word; smooth partial updates
Latency Budget & Round-Trip TargetsASR latency, network transit, inference, TTSASR: ≤150 ms, Inference: ≤400 ms, TTS: ≤200 ms, End-to-end p95: ≤500 ms
Interruptibility & Turn-TakingInterruption detection accuracy, reaction time, partial output cancellationDetection ≥90%, Reaction ≤100 ms, Cancellation success ≥95%
Context Window & Memory StrategyEffective context length, intent accuracy over turns, RAG retrieval latencyIntent drift ≤20%, RAG latency ≤100 ms
Model Size, Quantisation & HardwareVRAM usage, throughput (tokens/sec), accuracy delta after quantisationQuantisation loss ≤5%, Fit within deployment hardware
Safety, Hallucination & GuardrailsRed team pass rate, factual error rateRed team pass ≥95%, Factual errors ≤5%
License & Commercial Use RestrictionsLicense compliance, usage auditFull audit completed before deployment

Candidate open source LLMs to evaluate and how to map them to voice use cases

Candidate open source LLMs to evaluate and how to map them to voice use cases

When deciding which open source LLM to try for your voice agent, you must match the model family to your intended deployment scenario.

The “right” model for your use case must balance latency, fluency, memory, hardware, and domain fit. Here are three classes and how to evaluate them.

1. Small to Mid-Size Models for Edge / On-Device Inference

Use this class when latency and data privacy are critical. Good for IVRs, roadside support, etc., where you want inference locally or close to the user.

What to benchmark

  • VRAM and RAM requirements (e.g. <8-16 GB GPU, or 4-8 GB for CPU/edge)
  • Throughput in tokens/sec, especially under quantised modes
  • First response latency (e.g. first partial response under 300 ms)
  • Accuracy vs latency trade-offs, especially for common support queries

Model Recommendations for this Use Case

(small-mid parameter, open weights or permissive license)

Gemma-2B Google DeepMind Gemma-7B Google DeepMind Gemma 3 (Small) Google DeepMind
<a href="https://llama.meta.com/" target="_blank" class="llm-button" style="background-color: #fbcfe8; hover:background-color: #f472b6;">
    <span class="llm-name">Llama-3.2-1B (Instruct)</span>
    <span class="llm-family">Meta Llama</span>
</a>
<a href="https://llama.meta.com/llama-2/" target="_blank" class="llm-button" style="background-color: #fbcfe8; hover:background-color: #f472b6;">
    <span class="llm-name">LLaMA2 (Small 7B)</span>
    <span class="llm-family">Meta Llama</span>
</a>

<a href="https://mistral.ai/" target="_blank" class="llm-button" style="background-color: #fed7aa; hover:background-color: #fb923c;">
    <span class="llm-name">Mistral-7B</span>
    <span class="llm-family">Mistral</span>
</a>
<a href="https://mistral.ai/" target="_blank" class="llm-button" style="background-color: #fed7aa; hover:background-color: #fb923c;">
    <span class="llm-name">Mixtral-8×7B</span>
    <span class="llm-family">Mistral</span>
</a>
<a href="https://mistral.ai/" target="_blank" class="llm-button" style="background-color: #fed7aa; hover:background-color: #fb923c;">
    <span class="llm-name">Mixtral (Distilled)</span>
    <span class="llm-family">Mistral</span>
</a>

<a href="https://azure.microsoft.com/en-us/products/phi" target="_blank" class="llm-button" style="background-color: #99f6e4; hover:background-color: #2dd4bf;">
    <span class="llm-name">Phi-3 (3.8B)</span>
    <span class="llm-family">Microsoft Phi</span>
</a>
<a href="https://azure.microsoft.com/en-us/products/phi" target="_blank" class="llm-button" style="background-color: #99f6e4; hover:background-color: #2dd4bf;">
    <span class="llm-name">Phi (Small &lt;2B)</span>
    <span class="llm-family">Microsoft Phi</span>
</a>

<a href="https://www.deepseek.com/en" target="_blank" class="llm-button" style="background-color: #d9f99d; hover:background-color: #a3e635;">
    <span class="llm-name">DeepSeek-R1 (Distilled)</span>
    <span class="llm-family">DeepSeek</span>
</a>
<a href="https://www.deepseek.com/en" target="_blank" class="llm-button" style="background-color: #d9f99d; hover:background-color: #a3e635;">
    <span class="llm-name">DeepSeek (Small/Distilled)</span>
    <span class="llm-family">DeepSeek</span>
</a>

<a href="https://qwen.ai/" target="_blank" class="llm-button" style="background-color: #fbcfe8; hover:background-color: #f472b6;">
    <span class="llm-name">Qwen2.5 (Small &lt;4B)</span>
    <span class="llm-family">Qwen (Alibaba)</span>
</a>
<a href="https://qwen.ai/" target="_blank" class="llm-button" style="background-color: #fbcfe8; hover:background-color: #f472b6;">
    <span class="llm-name">Qwen (Quantised)</span>
    <span class="llm-family">Qwen (Alibaba)</span>
</a>

<a href="https://github.com/jzhang38/TinyLlama" target="_blank" class="llm-button" style="background-color: #d1d5db; hover:background-color: #9ca3af;">
    <span class="llm-name">TinyLlama (~1.1B)</span>
    <span class="llm-family">Open Source</span>
</a>
<a href="https://huggingface.co/EleutherAI/gpt-j-6b" target="_blank" class="llm-button" style="background-color: #d1d5db; hover:background-color: #9ca3af;">
    <span class="llm-name">GPT-J-6B</span>
    <span class="llm-family">Open Source</span>
</a>
<a href="https://huggingface.co/bigscience/bloom" target="_blank" class="llm-button" style="background-color: #d1d5db; hover:background-color: #9ca3af;">
    <span class="llm-name">BLOOM (7-xxB)</span>
    <span class="llm-family">Open Source</span>
</a>
<a href="https://falconllm.tii.ae/" target="_blank" class="llm-button" style="background-color: #d1d5db; hover:background-color: #9ca3af;">
    <span class="llm-name">Falcon-7B</span>
    <span class="llm-family">Open Source</span>
</a>
<a href="https://www.allenai.org/olmo" target="_blank" class="llm-button" style="background-color: #d1d5db; hover:background-color: #9ca3af;">
    <span class="llm-name">OLMo-1B</span>
    <span class="llm-family">Open Source</span>
</a>
<a href="https://github.com/OpenBMB/MiniCPM" target="_blank" class="llm-button" style="background-color: #d1d5db; hover:background-color: #9ca3af;">
    <span class="llm-name">GLM-edge / MiniCPM</span>
    <span class="llm-family">Open Source</span>
</a>

2. Medium to Large Models for Cloud Inference

Here, fluency, reasoning power, and high context matter more than on-device constraints. Use for escalated support, agents answering complex domain queries, or multilingual agents.

What to benchmark

  • Context window size (e.g. 16K tokens or more)
  • Cost of inference per token or per hour
  • Fluency / reasoning benchmarks (e.g. domain-specific QA accuracy)
  • Stability under load, throughput (tokens/sec), response consistency

Model Recommendations for this Use Case

Llama-3.1-70B Instruct Meta Llama Llama-3.3-70B Instruct Meta Llama (Future) Llama-4 Maverick-17B Meta Llama (Future) Llama-4 Scout-17B Meta Llama (Future) Llama-Guard-3-1B (Safety) Meta Llama
<!-- DeepSeek Family (Light Lime/Green: #d9f99d) -->
<a href="https://www.deepseek.com/en" target="_blank" class="llm-button" style="background-color: #d9f99d;">
    <span class="llm-name">DeepSeek-R1 Full MoE (~671B)</span>
    <span class="llm-family">DeepSeek AI</span>
</a>
<a href="https://www.deepseek.com/en" target="_blank" class="llm-button" style="background-color: #d9f99d;">
    <span class="llm-name">DeepSeek V3 Models</span>
    <span class="llm-family">DeepSeek AI</span>
</a>

<!-- Qwen / Alibaba Family (Light Red/Pink: #fecaca) -->
<a href="https://qwenlm.github.io/blog/qwen3/" target="_blank" class="llm-button" style="background-color: #fecaca;">
    <span class="llm-name">Qwen-3-235B A22B Instruct</span>
    <span class="llm-family">Qwen (Alibaba)</span>
</a>
<a href="https://qwenlm.github.io/blog/qwen3/" target="_blank" class="llm-button" style="background-color: #fecaca;">
    <span class="llm-name">Qwen-large / Qwen3 Large</span>
    <span class="llm-family">Qwen (Alibaba)</span>
</a>
<a href="https://qwenlm.github.io/blog/qwen3/" target="_blank" class="llm-button" style="background-color: #fecaca;">
    <span class="llm-name">Qwen-multilingual Large</span>
    <span class="llm-family">Qwen (Alibaba)</span>
</a>

<!-- Google DeepMind (Light Amber/Yellow: #fcd34d) -->
<a href="https://blog.google/technology/ai/gemma-2-family-announcement/" target="_blank" class="llm-button" style="background-color: #fcd34d;">
    <span class="llm-name">Gemma-27B</span>
    <span class="llm-family">Google DeepMind</span>
</a>
<a href="https://blog.google/technology/ai/gemini-25-pro-flash-announced/" target="_blank" class="llm-button" style="background-color: #fcd34d;">
    <span class="llm-name">Gemini-series Open</span>
    <span class="llm-family">Google DeepMind</span>
</a>

<!-- Mistral AI (Light Orange: #fed7aa) -->
<a href="https://mistral.ai/news/mixtral-8x22b/" target="_blank" class="llm-button" style="background-color: #fed7aa;">
    <span class="llm-name">Mixtral Large (8×7B variant)</span>
    <span class="llm-family">Mistral AI</span>
</a>

<!-- High-Capacity Open Source / Enterprise (Light Gray/Neutral: #d1d5db) -->
<a href="https://www.databricks.com/blog/introducing-dbrx-new-state-art-open-llm" target="_blank" class="llm-button" style="background-color: #d1d5db;">
    <span class="llm-name">DBRX (Databricks) 132B-class</span>
    <span class="llm-family">Databricks</span>
</a>
<a href="https://falconllm.tii.ae/" target="_blank" class="llm-button" style="background-color: #d1d5db;">
    <span class="llm-name">Falcon-40B / 180B</span>
    <span class="llm-family">TII/Open Source</span>
</a>
<a href="https://bigscience.huggingface.co/blog/bloom" target="_blank" class="llm-button" style="background-color: #d1d5db;">
    <span class="llm-name">BLOOM-176B</span>
    <span class="llm-family">BigScience</span>
</a>
<a href="https://github.com/TigerResearch/TigerBot" target="_blank" class="llm-button" style="background-color: #d1d5db;">
    <span class="llm-name">TigerBot-70B / 180B</span>
    <span class="llm-family">Tiger Research</span>
</a>
<a href="https://h2o.ai/platform/h2o-llm-studio/" target="_blank" class="llm-button" style="background-color: #d1d5db;">
    <span class="llm-name">H2O-GPT (40B)</span>
    <span class="llm-family">H2O.ai</span>
</a>
<a href="https://github.com/THUDM/GLM" target="_blank" class="llm-button" style="background-color: #d1d5db;">
    <span class="llm-name">GLM Large / GPT-OSS</span>
    <span class="llm-family">Open Source</span>
</a>

3. Hybrid Options & Fine-Tuned / Retrieval-Augmented Variants

Use this class to boost domain accuracy (telco, finance, healthcare) and maintain conversational quality. Often involves fine-tuning, RAG, and knowledge bases.

What to benchmark

  • Retrieval latency + freshness of documents
  • Quality of domain responses vs generic responses
  • Memory usage when using RAG pipelines
  • Delay added by fine-tuning overhead or embedding lookups

Model Recommendations for hybrid / fine-tuned variants

DeepSeek-R1 with **Domain Fine-Tuning**
Llama-3 Instruct with **RAG over Support KB**
Falcon Fine-tuned on **Telecom Dialogues**
H2O-GPT **Domain-Specific Tuning**
TigerBot Variants with Chat + **Domain Data**
Mixtral-8×7B Instruct **Fine-Tuned** (MoE)
Gemma Small with **Legal/Telco Datasets**
Qwen Large

Integration Blueprint: ASR, LLM, TTS and orchestration

Integration Blueprint: ASR, LLM, TTS and orchestration

Picture the voice AI pipeline as a relay team. The first runner is ASR (Automatic Speech Recognition) grabbing the customer’s audio and sprinting to turn it into text.

That text then hands the baton to the LLM, the brain of the operation, deciding what to say next. Finally, TTS (Text-to-Speech) voices the response with a human-like tone.

But here’s the trick: call centers/customer support need speed and grace. Rather than waiting for the whole transcript, modern systems use streaming orchestration.

The ASR sends partial transcriptions, the LLM starts crafting a response mid-stream, and TTS begins speaking even before the full sentence lands.

Libraries like Deepgram, Vosk, or OpenAI Whisper for ASR, vLLM or Text Generation Inference for LLM hosting, and Coqui TTS or OpenTTS for speech synthesis help stitch this together quickly.

A session manager keeps track of who said what. It juggles conversational context and short-term memory so the bot doesn’t greet you twice or forget your billing question halfway through.

Fallback layers handle dead air, unexpected errors, or model slowdowns. They achieve this by routing to scripted responses or a human agent, preserving the user experience.

For orchestration, frameworks like LangChain, Haystack, or even n8n help you manage streaming flows, progressive responses, and event triggers. This capability allows you to handle complex processes without having to hand-craft every single API call.

Together, these patterns create a responsive voice AI agent that feels seamless rather than robotic, even when the backend is a symphony of moving parts.

Why ConnexCS’s AI Voice Agent is a Smarter Starting Point

Open-source LLMs offer a lot of flexibility. But building a voice AI stack from scratch involves model orchestration, latency optimization, real-time streaming, and rigorous testing.

ConnexCS’s AI Voice Agent packages all these complexities into a production-ready platform without stripping away control or customizability. We’ve integrated open-source LLM capabilities, pre-tuned for sub-second interactions, domain-specific fine-tuning, and seamless ASR–TTS pipelines.

Instead of spending months assembling infrastructure, businesses can launch quickly, adapt features on demand, and scale confidently. All while retaining the same freedom and cost benefits as open-source development. And without the engineering overhead or time-to-market delays typically associated with building an AI voice agent ground up.

Try ConnexCS’s AI Voice Agent for all the flexibility, none of the drama, and zero sleepless nights staring at GPU logs.